This observational cross-sectional study aims to evaluate the prevalence of endodontic procedural errors in root canal-treated teeth among an Egyptian subpopulation using cone-beam computed tomography (CBCT). The study will analyze CBCT scans obtained from radiology centers in Cairo to detect errors such as missed canals, short fillings, perforations, fractured instruments, and other complications. Understanding the frequency and distribution of these errors between the maxillary and mandibular arches may help improve endodontic treatment outcomes and raise awareness of common procedural challenges. The study does not involve any new treatment or drug but will rely on previously taken CBCT images.

The biological and therapeutic goals of Endodontic treatment are to prevent apical lesions or to establish ideal healing conditions by removing bacteria and infection from the root canal system and preventing reinfection. However, endodontic mishaps such as incorrect diagnosis, missed canals, perforations, instrument separation, over- or under-obturation, and vertical root fractures compromise the success of root canal therapy.

The reported success rate of endodontic treatments by general dentists ranges from 60% to 75%. Procedural errors are a significant factor contributing to the suboptimal success rate of endodontic treatments performed by general dentists. Moreover, the global prevalence of periapical lesion is approximately 52% in individuals and 5% in teeth, with higher frequency in teeth with root-filled teeth compered to non-treated teeth.

Procedural errors may be difficult to correct. Certain procedural errors could need endodontic retreatment, apicoectomy, or even tooth extraction. Root canal transportation, apical perforation, strip perforation, access cavity perforation, and instrument fracture are among the commonly occurring procedural errors. The working length of the root canal filling is a critical factor, with fillings short of the apex by 2 mm reducing success rates to 68-77% and overfills beyond the apex yielding around 75% success rates.

Endodontic treatment for molar teeth is more challenging and requires more caution than anterior and premolar teeth, and is associated with a higher rate of procedural errors. The reason for this is their difficulty in accessibility and anatomical complexity. This is reflected in the distribution of errors, were Procedural errors were more frequently observed in mandibular teeth (53.1%) than maxillary teeth (46.9%), with the highest error rate found in the right and left permanent mandibular first molars (20.2% and 14.3%, respectively).

Cone-beam computed tomography (CBCT) it delivers high-quality images and images providing three-dimensional imaging, allowing detailed views of individual teeth from any angle. This makes it an effective tool for diagnosing, planning, and monitoring endodontic treatment. CBCT can detect periapical radiolucency before they would be apparent on conventional radiographs. While traditional radiographs are less expensive and expose patients to lower radiation doses, research has demonstrated that CBCT images are better for diagnosing periapical lesions.

Rationale for conducting the research:

In Egypt, there is a lack of comprehensive data regarding the prevalence and distribution of procedural errors in endodontically treated teeth. This knowledge gap limits our understanding of how these errors differ between the maxilla and mandible and restricts the development of targeted strategies to enhance treatment quality and reduce failure rates.

Despite significant advancements in endodontic techniques and imaging modalities, procedural errors remain a critical challenge in achieving optimal treatment outcomes. These errors are particularly problematic in molar teeth due to their anatomical complexity and reduced accessibility. Although several international studies have evaluated the prevalence of endodontic procedural errors, there is limited research focusing specifically on the Egyptian subpopulation.

Understanding the patterns and frequencies of procedural errors in maxillary and mandibular teeth among Egyptians can aid clinicians in anticipating challenges, refining treatment strategies, and minimizing procedural failures. Moreover, differences in error distribution between the two jaws reported in other populations highlight the need for local investigation.

CBCT technology provides a detailed three-dimensional assessment of dental anatomy and procedural errors, offering superior diagnostic capabilities compared to two-dimensional radiography. This makes it an ideal tool for evaluating the prevalence and distribution of endodontic procedural errors.

Therefore, the aim of this study is to determine the prevalence and distribution of endodontic procedural errors in the maxilla and mandible using CBCT imaging in a selected Egyptian subpopulation.

Inclusion Criteria:

• CBCT scans showing at least one permanent tooth that has undergone complete root canal treatment.
• Scans showing both jaw (maxilla and mandible) .
• Scans with good image quality and a voxel size of 0.2 mm or 0.3 mm.
• Egyptian nationals of either gender.
• Age over 18 years.

Exclusion Criteria:

• CBCT scans that do not show any teeth with complete root canal treatment.
• Completely edentulous patient.
• Low-quality images or scans with artefacts.
• Scans with voxel size larger than 0.3 mm.
• Non- Egyptian patients.
• Surgically treated endodontic cases (e.g., apicoectomy).

The study population consists of 379 CBCT scans obtained from Egyptian adult patients (over 18 years old) of both genders. These scans were acquired from radiology centers across Cairo, where patients were referred for various diagnostic purposes. The included scans represent cases with at least one fully endodontically treated permanent tooth and acceptable image quality